Internal combustion percussion tool and hammer piston locking means therefor



Jan. 28, 1969 5, wl 3,424,252

INTERNAL COMBUSTION PERCUSSION TOOL AND HAMMER v PISTON LOCKING MEANS THEREFOR Filed Sept. 1, 3.967 Sheet of 2 I INVENTOR. Sven ERIK WicKlund WW w...

Jan. 28, 1969 s, w c 3,424,252

INTERNAL COMBUSTION PERCUSSION TOOL AND HAMMER PISTON LOCKING MEANS THEREFOR Filed Sept. 1, 1967 Y Sheet 2 of 2 Fig.4

Fig.6-

INVEN'IOR. Sven ERiK WicKlund BY w I! United States Patent 3,424,252 INTERNAL COMBUSTION PERCUSSION TOOL AND HAMMER PISTON LOCKING MEANS THEREFOR Sven Erik Wicklund, Saltsjobaden, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed Sept. 1, 1967, Ser. No. 664,985 Claims priority, application Sweden, Sept. 6, 1966,

11,955/ 66 US. Cl. 173-116 Int. Cl. E21c 3/18; B25d 9/10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to internal combustion percussion tools and more particularly to internal combustion precussion tools and hammer piston locking means therefor. In many cases it is desirable to use percussion tools or machines of the above type as prime movers for driving various accessory apparatus from the crankshaft of the motor piston forming part of the percussion tool. Accessory devices suitable for such use are for example grinding wheels for the sharpening of rock drill steels, immersion vibrators for concrete and drain pumps. It is a desideratum in connection herewith to stop the reciprocation of the free hammer piston in order to avoid energy losses so that the work delivery :by the motor piston will be at an optimum, Locking arrangements for the hammer piston of internal combustion permussion tools have been used before. Examples of such locking arrangements are given in the specifications of US. Pat ents 1,308,811, to L. L. Scott and 2,764,138 to G. L. B. Wahlsten et al. The primary purpose of these prior art locking arrangements, however, has been to facilitate starting of the motor part of the tool and they do not allow fixing of the hammer piston in such manner as to make possible running of the motor with increased speed and the elimination of pulsations and jolts and the accompanying energy losses in the operation of the motor piston.

It is the primary object of the invention to increase in an internal combustion percussion tool the output of the motor forming part of the tool so that accessory apparatus driven from the crankshaft of the motor when the latter is used as a prime mover can be operated optimally at increased speed. Another object of the invention is to create an internal combustion percusssion tool and hammer piston locking means therefore in which the locking means are of simple and dependable construction and adapted for immobile and positive locking of the hammer piston in the percussion tool in a position ensuring optimum work and increased speed of the motor part of the tool. For these and other purposes there is according to the invention provided an internal combustion percussion tool comprising a tool housing, a working cylinder in said housing, a motor piston reciprocable in said cylinder, a free hammer piston in communication with said working cylinder and "ice reciprocable in said housing in dependance upon the reciprocation of said motor piston, an impact delivering end on said hammer piston, supporting surfaces fixedly connected to said housing, a lock member engaging said impact end and said supporting surfaces, and means for clamping said lock member between said impact end and said surfaces for applying a clamping force to the hammer piston to immobilize the latter in said housing. By reason of the clamping the hammer piston obtains an initial load eliminating its movements due to the pulsation forces. Simultaneously the load is applied against a portion of the hammer piston, which constructionally on the one hand is easily accessible and on the other is per se intended to well endure clamping or squeezing forces.

The above and other objects of the invention will become obvious from the following description and from the accompanying drawing in which a number of preferred embodiments of the invention are illustrated by way of example. It should be understood that these embodiments are only illustrative of the invention andvarious further modifications may be made within the scope of the claims.

In the drawing FIG. 1 shows a longitudinal section through the lower end of a percussion tool embodying the invention. FIG. 2 is a section on the line 2-2 in FIG. 1. FIG. 3 is a fragmentary side view of the tool in FIG. 1 seen in the direction of the arrows 33. FIG. 4 is a fragmentary section on the line 4-4 in FIG. 3. FIG. 5 shows a partial longitudinal section through a percussion tool with a modified embodiment of the invention. FIG. 6 shows a partial longitudinal section of a percussion tool with another embodiment of the invention. FIG. 7, finally, shows a partial longitudinal section similar to the one shown in FIG. 6 but of a still further embodiment of the invention.

In the drawings there is illustrated an internal combustion percussive machine or percussion tool having a housing generally designated 10 and provided with a motor piston 12 reciprocable in a combustion working cylinder 11. The motor piston 12 is tied by means of a connecting rod 15, FIG. 5, to the crankshaft, not shown, of the percussion tool. A hammer piston 13 is freely reciprocable in the housing 10 in dependance upon the movements of the rotor piston 12 to which end the hammer piston communicates with the working cylinder 11. The hammer piston 13 strikes the neck of a tool implement 14 received in the housing 10 and retained by a tool holder 41. The design and function of the percussion tool illustrated is conventional and well known in the art and will therefore not be described in more detail here.

When it is desired to drive a grinding wheel, a drain pump or other accessory units of machinery from the crankshaft of the percussion tool, the reciprocation of the hammer piston 13 should be stopped in order to enable the motor piston 12 to work with a minimum of losses. To this end there are in an intermediate portion 16 of the housing 10, FIGS. 14, provided aligned and coplanar, transverse and slightly inclined supporting surfaces 17, 18 at opposite sides of the path of movement of the stem 19 and impact end 20 of the hammer piston 13. The supporting surfaces 17, 18 are constituent parts of a recess 21 projecting laterally into the intermediate portion 16, which recess may be closed to the outside by means of a tightly fitting cover 22. The cover 22 is swinga'bly mounted on a pin 23 fastened to the outside of the intermediate portion 16 adjacent to the recess 21. During operation of the hammer piston 13 flushing air is supplied from a suitable source in the machine 10 to the neck of the tool 14, in case the latter is a drill steel equipped with an axial flushing passage. For keeping the cover 22 in a closed position against the prevailing flushing air pressure in the recess 21, which receives flushing air for example through a side bore 40 from the interior of the intermediate portion 16, there is strained a leaf spring 24 between the pin 23 and the outside of cover 22.

In order to lock the hammer piston 13 in its upper dead center poistion, FIG. 1, i.e. in a position nearest to the path of the motor piston, the cover 22 is turned aside, while the machine 10 is at a standstill, from the position in FIG. 4 to the position in FIG. 3, whereupon a lock member or wedge is forcibly clamped between the supporting surfaces 17, .18 and the impact end 20 of the hammer piston 13. The wedge consists of two parts 25, 28 movable relative to one another. One of these parts 25, 28 is a wedge shaped body 25 which, through actuation of clamping means consisting of a screw 27 carrying a knob 26, can be displaced slidably along an angle bar 28 forming the other part of the split wedge. The one shank of the angle bar 28 is passed freely rotatably by the screw 27 whilst the wedge body 25 by means of a screw 29 is bound to follow a slot 30 machined in the shank of the angle bar 28 adjacent to the wedge body 25. When the wedge parts 25, 28 are inserted in the recess 21, the angle bar 28 is placed against the supporting surfaces 17, 18, whereupon the wedge is clamped forcibly against the impact end 20 of the hammer piston 13 by actuation of its clamping means consisting of the knob 26 and the screw 27 connected thereto. The slideability of the wedge body 25 on the angle bar 28 eliminates the need of driving in the wedge 25, 28 or extracting it by impacts of a hammer, which impacts could damage the recess 21 and the intermediate portion 16. The wedge 25, 28 makes possible immobilization of the hammer piston 13 under a clamping load in a position ensuring that the motor piston will render maximum work with small energy losses.

In the embodiment illustrated in FIG. in the tool housing there is rotatably journalled in front of the hammer piston 13 an eccentric 31 carried on an eccentric shaft. Said shaft is rotatably journalled at the opposite ends thereof in supporting surfaces or bushings 17', 18. When one desires to lock the hammer piston 13, the shaft together with the eccentric 3.1 is inserted from the outside axially into bushings 17', 18 and then turned by means of an outside clamping handle 32 which is brought against a stop 33. During turning of the handle 32 the eccentric 31 will be turned up against the impact end of the hammer piston 13 whereby the hammer piston 13 will be clamped fast. When one desires to release the locking, the eccentric 31 is turned free by means of the handle 32 and pulled out axially through the bushing 17'. Thereupon the openings in bushings 17', 18' are sealed by suitable covers or plugs, not shown, the percussion tool then being ready for ordinary percussive work.

In the embodiment illustrated in FIG. 6 the impact end 20 of the hammer piston 13 is clamped by a screw spindle 35 coaxial with the hammer piston 13 which spindle 35 can be tightened against the impact end 20 of the piston. The screw spindle 32 is threaded in a sleeve 36 forming part of a strap 37. The strap 37 is fixed at the front end of the housing 10 of the percussion tool by means of pins 38. The clamping results from turning of the spindle 35 in the female threads of the sleeve 36 to which end the spindle 35 may be provided with a wing nut end or the like.

In the embodiment illustrated in FIG. 7 the percussion tool is similar to the embodiment shown in FIG. 1 and provided with a tool holder 41 of conventional design in the shape of a yoke 41 partially encircling in the retaining position of the tool holder 4.1 the shank of the tool implement 14 to be struck by the hammer piston 13. The tool holder 41 is pivotally journalled on a pivot 45 supported by the housing 10 of the percussion tool and can take a release position, not shown, closely adjacent to the housing 10, in which release position the tool implement 14 may be removed from the tool chuck 43 in the housing 10. With the tool implement 14 removed, the hammer piston 13 is clamped fast by means of a threaded spindle 35, which carries adjusting and clamping nuts 42 thereon for cooperation with opposite surfaces on the tool encircling end of the yoke 41. The spindle 35 is received guidingly in the tool chuck 43 in the housing 10 of the percussion tool and the yoke 41 is arrested against outward turning from the retaining position thereof relative to the housing 10 for example by abutments 44 cooperating with the ends of the yoke adjacent to the pivot 45.

What I claim is:

1. An internal combustion percussion tool comprising a tool housing, a working cylinder in said housing, a motor piston reciprocable in said cylinder, a free hammer piston in communication with said working cylinder and reciprocable in said housing in dependance upon the reciprocation of said motor piston, an impact delivering end on said hammer piston, supporting surfaces fixedly connected to said housing, a lock member engaging said impact end and said supporting surfaces, and means for clamping said lock member between said impact end and said surfaces for applying a clamping force to the hammer piston to immobilize the latter in said housing.

2. A percussion tool according to claim 1 in which said supporting surfaces are aligned transversely in said housing at opposite sides of the path of movement of said impact end.

3. A percussion tool according to claim 2 in which said lock member is a wedge insertable in front of said hammer piston in said housing transversely between said aligned supporting surfaces.

4. A percussion tool according to claim 3 in which said wedge is split in the longitudinal direction thereof in two relatively movable parts, said clamping means being a tightening screw cooperating with said parts for applying a clamping force to said hammer piston.

5. A percussion tool according to claim 2 in which said lock member is an eccentric, a shaft carrying said eccentric and disposed transversely in front of said impact end, said aligned surfaces being bearing surfaces in which said shaft is rotatably journalled, and said clamping means being handle means for turning said shaft and eccentric to clamp said hammer piston.

.6. A percussion tool according to claim .1 in which said lock member is a threaded spindle in front of said impact end and coaxial with said hammer piston, a member supported by said housing in front of said hammer piston, said supporting surfaces being female threads provided in said member and engaged by the threads of said spindle, and said clamping means being turning means for said spindle.

7. A percussion tool according to claim 1 in which said lock member is a threaded spindle in front of said impact end and coaxial with said hammer piston, a tool holder supported by said housing in front of said hammer piston and providing said supporting surfaces, and at least one nut on said threaded spindle engaging said tool holder for clamping said spindle between said impact end and said supporting surfaces on said tool holder.

8. Internal combustion percussion tool comprising a tool housing, a working cylinder in said housing, a motor piston reciprocable in said cylinder, a free hammer piston in communication with said working cylinder and reciprocable in said housing in dependance upon the reciprocation of said motor piston, an impact delivering end on said hammer piston, a transverse recess in said housing intersecting the path of movement of said impact end, and a wedge insertable into said recess forcibly between said impact end and the walls of said recess opposed thereto for applying a clamping force to the hammer piston to immobilize the latter in said housing.

9. An internal combustion tool according to claim 8 in which said recess in said housing has an end open to the outside of said tool for the insertion or removal of said wedge, and cover means on said housing movably mounted thereon for closing said open end of said recess when said wedge is removed therefrom.

10. An internal combustion percussion tool comprising a tool housing, a working cylinder in said housing, a motor piston reciprocable in said cylinder, a free hammer piston in communication with said Working cylinder and reciprocable in said housing in dependance upon the reciprocation of said motor piston, an impact delivering end on said hammer piston, a tool chuck in said housing in front of said hammer piston for receiving the neck of a tool implement therein to be struck by said impact end, a tool holder supported by said housing for removably retaining said tool implement in said tool chuck, a threaded spindle insertable, when said tool implement is removed from said tool chuck, into said tool chuck against said impact end of said hammer piston, and a pair of nuts on said threaded spindle engaging said tool holder for clamping said spindle between said impact end and said tool holder for applying a clamping force to the hammer piston to immobilize the latter in said housing.

References Cited UNITED STATES PATENTS 1,308,811 7/1919 Scott 173-121 2,764,138 9/1956 Wahlsten et al 1731l0 3,154,154 10/1964 Wicklund 1731 16 JAMES A. LEPPINK, Primary Examiner.

US. Cl. X.R. 173-137 

